The present invention is directed to a method and apparatus for cracking nuts of the type having very hard shells such as macadamia nuts or walnuts. In the past a great deal of skill was required to crack nuts having a kernel such as macadamia nuts in a highly efficient manner without damaging the kernels.
U.S. Pat. No. 4,135,442 discloses a nut cracking machine wherein a nut is held between two dish-shaped dies. Means are provided for applying a sudden impact to one of the dies thereby causing the die to move a limited distance to crack the nut. When the nut is cracked or crushed in this manner, the shell scatters and the kernel of the nut is in danager of being damaged. The cracking machine makes it impossible to divide the shell into two pieces without damaging the kernel.
U.S. Pat. No. 4,200,042 discloses a nut cracker having first and second levers which are pivotally connected together at one end and have opposed portions provided with one or more cross-grooves for receiving nuts to be cracked. These grooves have a varying depth from one end to the other and also have a varying width thus accommodating a wide range of nut sizes. The grooves also have transverse ribs to hold the nuts in place while being cracked and in a preferred structure, the grooves are defined by straight wall segments meeting in angular relation. One of the levers may comprise a base portion and the other lever may include a handle for applying leverage. When the nuts are placed in these grooves and the levers brought together, the nuts are crushed without cutting the shell so that there is a distinct possibility that the kernels of the nuts will be damaged because of the scattering of the shell.
In the past the cracking of nuts was generally a laborious and time consuming operation even when using the apparatus disclosed in the two above-identified patents. The nuts were usually cracked one-by-one and some element of manual labor was generally required.